Nickyct, broadband over powerline is a neat idea, and it works in research trials, but in the real world it's not working so well.
Telcos and cable companies are both currently investing a whole lot of resources into getting fiber to the home (Verizon) or at least to the neighborhood (cable cos, AT&T). So folks who have communication-grade cabling are hitting the wall of what they can do with it, and replacing all or most of it with fiber, in order to remain competitive. Power lines and power distribution equipment (transformers, load switches, etc.) are most definitely not communication-grade. It's not realistic to believe that you can move data across those lines and that equipment and end up with performance that would be competitive with fiber to the neighborhood. It's already proven to be very iffy to get data performance that could compete with DSL and cable data services, and that's in limited trials, not widespread deployment.
The only realistic use I can see of BPN is as a last-mile solution from the neighborhood fiber node to the home. But even then it's proven to be inferior to telco twisted-pair cable and coax cable.
If you're looking for a "third pipe" solution, I think that wireless (e.g., WiMax) is a much more realistic medium than powerline. I won't say that powerline can't happen, but right now all indications is that it won't be competitive with the telco and cable options.